TABLE 2.

Comparative sequence alignment of the M2 domain and M2–M3 linker region of each subunit

						0′										10′
α1	251	S	V	P	A	R	T	V	F	G	V	T	T	V	L	T	M
β2	246	A	S	A	A	R	V	A	L	G	I	T	T	V	L	T	M
γ2	261	A	V	P	A	R	T	S	L	G	I	T	T	V	L	T	M
			13′						19′
α1	267	T	T	L	S	I	S	A	R	N	S	L	P	K	V	A	Y
β2	262	T	T	I	N	T	H	L	R	G	T	L	P	K	I	P	Y
γ2	277	T	T	L	S	T	I	A	R	K	S	L	P	K	V	S	Y

The top row of numbers gives the universal indexing system, whereas the number on the left of each row is the subunit-specific number of the first residue of each aligned sequence. The pore-lining residues of the homology model are underlined, whereas the experimentally determined pore-lining residues identified by Xu and Akabas (1996) and Bera et al. (2002) are in bold text.